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THREE TRILLION TREES ON EARTH

(P1) There are just over three trillion trees on Earth, according to a new study.

(P2) The figure is eight times as big as the previous best ESTIMATE, which counted perhaps 400 billion at most.

(P3) It has been produced by Thomas Crowther from Yale University and his colleagues, who combined a MASS of ground survey data with satellite pictures.

(P4) The team tells the journal Nature that the new total represents UPWARDS of 420 trees for every person on the planet.

(P5) Dr Crowther CAUTIONED that the higher number did not of itself change anything: “It’s not like we’ve discovered new trees.

(P6) “So, it’s not good news for the world or bad news that we’ve produced this new number.

(P7) “We’re simply describing the state of the global forest system in numbers that people can understand and that scientists can use, and that environmental PRACTITIONERS or POLICY-makers can understand and use.”

(P8) The team collected tree DENSITY information from over 400,000 forest PLOTS around the world.

(P9) This included many national forest INVENTORIES and a host of PEER-REVIEWED studies where workers had actually gone out and counted the number of trees in a given area and in a given forest type.

(P10) This then ENABLED Dr Crowther and his group to build a model that better characterised what they were seeing in satellite pictures, which are very good at showing forest EXTENT but are not so good at REVEALING just how many individual trees there are.

(P11) Of their approximately 3,040,000,000,000 trees, the scientists put most (1.39 trillion) in the tropics and sub-tropics, 0.61 trillion in TEMPERATE regions, and 0.74 trillion in the BOREAL FORESTS – that great band of CONIFERS that circles the globe just below the Arctic.

(P12) Indeed, it is in the boreal forests that they say the greatest densities are seen.

(P13) What is ABUNDANTLY clear from the study is the influence humans now have on the number of trees on Earth. The team estimates we are removing about 15 billion a year, with perhaps only five billion being planted back.

(P14) “The net loss is about a third of a percent of the current number of trees globally,” said co-author Dr Henry Glick.

(P16) “And where tree losses are often tied to TIMBER supplies and LAND USE conversion for agriculture, as the global human population grows, we may see the net loss increase as well.”

(P17) And as if to emphasise this point, a comparison with estimates of ANCIENT forest cover suggests that humanity could have already removed almost three trillion trees since the last ice age, some 11,000 years ago.

(P18) “Europe used to be almost covered by one giant forest and now it’s almost entirely fields and grasslands. Humans are absolutely controlling tree densities,” Dr Crowther told BBC News.

If you found the passage difficult to read or had problems understanding specific words or idiomatic expressions, please discuss them with your tutor. The following discussion questions should be answered in your own words and with your own arguments.

Briefly summarize the content of the article in your own words.

Parks with trees are important features of most cities. Why are trees important to people’s health?

What is your favorite type of tree?

Have you ever lived on a property with trees?

Do you enjoy going to the forest to hike and camp?

EXPRESSIONS TO PRACTICE:

What do the following expressions mean? Practice using each expression in a sentence; extra points if you can use it in conversation.